In 1937 Harefield House was bought by the Air Ministry for use as a
“Test House” for the Aeronautical Inspection Directorate (AID) -
[later called the Aeronautical Quality Assurance Directorate (AQD)]
Recruitment started in 1938 and a diary was kept of the people who started work in this rather secretive facility. When it closed in the early 1980s the two volume diary found its way into the HHS archive.
It has now been digitised :-